Method of encapsulating packaged microelectronic devices with a barrier

ABSTRACT

Methods and apparatuses for encapsulating a microelectronic die or other components in the fabrication of packaged microelectronic devices. In one aspect of the invention, a packaged microelectronic device assembly includes a microelectronic die, a substrate attached to the die, a protective casing covering a portion of the substrate, and a barrier projecting away from the surface of the substrate. The microelectronic die can have an integrated circuit and a plurality of bond-pads operatively coupled to the integrated circuit. The substrate can have a cap-zone defined by an area that is to be covered by the protective casing, a plurality of contact elements arranged in the cap-zone, a plurality of ball-pads arranged in a ball-pad array outside of the cap-zone, and a plurality of conductive lines coupling the contact elements to the ball-pads. The contact elements are electrically coupled to corresponding bond-pads on the microelectronic die, and the protective casing covers the cap-zone. The barrier on the surface of the substrate is configured so that at least a portion of the barrier is outside of the cap-zone and adjacent to at least a portion of the molded section. The barrier is a seal that inhibits the thermosetting material of the protective casing from covering a portion of the substrate outside of the cap-zone. As such, the barrier prevents thermosetting material from leaking between the substrate and a mold outside of the cap-zone during a molding process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/970,399 filed Oct. 20, 2004, now U.S. Pat. No. 7,101,737 issued Sep.5, 2006, which is a divisional of U.S. patent application Ser. No.09/649,428 filed Aug. 28, 2000, now U.S. Pat. No. 6,838,760 issued Jan.4, 2005, both of which are incorporated herein by reference in theirentireties.

TECHNICAL FIELD

The present invention relates to packaging microelectronic deviceshaving a microelectronic die including an integrated circuit. Moreparticularly, several aspects of the invention are related to aninterconnecting unit for operatively coupling the microelectronic die tovoltage sources, signal sources, and other input/output sources.

BACKGROUND

Microelectronic devices, such as memory devices and microprocessors,typically include a microelectronic die encased in a protectivecovering. The die can include memory cells, processor circuits,interconnecting circuitry and/or other functional features. The die alsotypically includes an array of very small bond-pads electrically coupledto the functional features. When the die is packaged, the bond-pads arecoupled to leads, solder ball-pads or other types of terminals foroperatively coupling the microelectronic dies to buses, circuits and/orother microelectronic devices.

Several different techniques have been developed for packagingmicroelectronic dies. The dies, for example, can be incorporated intoindividual packages, mounted with other components in hybrid or multiplechip modules, or connected directly to a printed circuit board or othertypes of substrates. When a die is incorporated into an individualpackage, the bond-pads on the die are typically coupled to a lead frame,and the die is covered or otherwise sealed from the environment. Whenthe die is attached directly to a printed circuit board or another typeof substrate, the bond-pads on the die are typically coupled tocorresponding contact elements on the substrate using wire-bond lines,ball grid arrays and other techniques. The dies that are mounteddirectly to the substrates are generally Chip Scale Package devices(CSP) or Flip Chip Bare Die devices (Flip-Chip).

CSP and Flip-Chip devices generally have one or more protective casingsthat encapsulate the dies and any exposed contact elements, bond-pads orwire-bond lines. The protective casings should shield the die and theother components on the substrate from environmental factors (e.g.,moisture), electrical interference, and mechanical shocks. Theprotective casings are accordingly robust elements that protect thesensitive components of a microelectronic device. The protective casingsare generally composed of plastics, ceramics, or thermosettingmaterials.

One conventional technique for fabricating the protective casingsinvolves placing the die in a cavity of a mold, and then injecting athermosetting material into the cavity. The thermosetting material flowsover the die on one side of the substrate until it fills the cavity, andthen the thermosetting material is cured so that it hardens into asuitable protective casing for protecting the die. The protective casingshould not have any voids over the die because contaminants from themolding process or environmental factors outside of the mold coulddamage the die. The thermosetting material, moreover, should not cover aball-pad array on the substrate or damage any electrical connectionsbetween the die and the substrate. Therefore, the thermosetting materialshould be molded in a manner that avoids (a) producing voids in theprotective casing, (b) covering certain portions of the substrate, and(c) displacing or otherwise damaging any wire-bond lines or solderjoints between the die and the substrate.

One drawback of forming protective casings is that the thermosettingmaterial may leak between the substrate and a mold assembly as thethermosetting material fills the mold. The thermosetting materialgenerally leaks because the substrates can have small surface asperitiesand/or be warped. Such leaking of the thermosetting material can coverball-pad arrays and/or adhere to the mold. When the thermosettingmaterial covers a portion of the ball-pad array, the packaged device istypically rejected because it cannot be electrically coupled to amodule. Additionally, the molds must be cleaned periodically to removethe thermosetting material that adheres to the mold. Cleaning the molds,however, is difficult because they operate at approximately 180° C., andthus they are difficult to handle and they must also be reheated afterthey have been cleaned. The down time for cleaning a mold can beapproximately 15% of the available operating time for a molding machine.Therefore, it would be desirable to prevent the thermosetting materialfrom leaking between the substrate and the mold.

One technique that addresses the leakage between the substrate and themold is to cover the inside of the mold with a thin plastic film. Thistechnique, however, is time consuming because the mold must generally becooled to a temperature at which it can be handled, and it is difficultto attach the plastic film to the mold without creating wrinkles in theplastic film. Moreover, if the plastic film has wrinkles, the resultingprotective casings may have surface asperities that are either unsightlyor impair the performance of the protective casing. Therefore, coveringthe inside of a mold with a thin plastic film is not a good solution forpreventing the thermosetting material from leaking between the substrateand the mold.

SUMMARY

The present invention is directed toward methods and apparatuses forencapsulating a microelectronic die or other components in thefabrication of packaged microelectronic devices. In one aspect of theinvention, a packaged microelectronic device assembly includes amicroelectronic die, a substrate attached to the die, a protectivecasing covering a portion of the substrate, and a barrier projectingaway from the surface of the substrate. The microelectronic die can havean integrated circuit and a plurality of bond-pads operatively coupledto the integrated circuit. The substrate can have a cap-zone defined bythe area covered by the protective casing, a plurality of contactelements arranged in the cap-zone, a plurality of ball-pads arranged ina ball-pad array outside of the cap-zone, and a plurality of conductivelines coupling the contact elements to corresponding ball-pads. Thebarrier is configured so that at least a portion of the barrier isoutside of the cap-zone and adjacent to at least a portion of the moldedsection. The barrier, for example, can be a thin tape applied to thesubstrate, a polymeric coating covering the substrate, another type ofthin film disposed on the substrate, or a ridge formed from thesubstrate itself. The barrier can have an opening with an edge thatborders the cap-zone so that the area of the cap-zone is not covered bythe barrier. In operation, the barrier inhibits the thermosettingmaterial from covering a portion of the substrate outside of thecap-zone. As such, the barrier prevents or at least inhibits thethermosetting material from leaking between the substrate and a moldoutside of the cap-zone during a molding process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is top cut-away isometric view of a microelectronic devicebefore being packaged in accordance with one embodiment of theinvention.

FIG. 1B is a bottom isometric view of the microelectronic device of FIG.1A.

FIG. 2A is a side cross-sectional view of the microelectronic device ofFIG. 1A being packaged in accordance with an embodiment of theinvention.

FIG. 2B is a front cross-sectional view of the microelectronic device ofFIG. 2A being packaged in accordance with an embodiment of theinvention.

FIG. 3 is a top isometric view of a packaged microelectronic device inaccordance with an embodiment of the invention.

FIG. 4 is a top isometric view of a microelectronic device before beingpackaged in accordance with another embodiment of the invention.

FIG. 5A is a top isometric view of a packaged microelectronic device inaccordance with another embodiment of the invention.

FIG. 5B is a bottom isometric view of the packaged microelectronicdevice of FIG. 5A.

FIG. 6 is a top isometric view of a microelectronic device before beingpackaged in accordance with yet another embodiment of the invention.

DETAILED DESCRIPTION

The following disclosure is directed toward packaged microelectronicdevices, interconnecting units for packaged microelectronic devices, andmethods for encapsulating a microelectronic die, wire-bond lines orother components of a microelectronic device. Several embodiments of theinvention are described with respect to memory devices, but the methodsand apparatuses are also applicable to microprocessors and other typesof devices. One skilled in the art will accordingly understand that thepresent invention may have additional embodiments, or that the inventionmay be practiced without several of the details described below.

FIG. 1A is a top cutaway isometric view of a microelectronic device 10in accordance with one embodiment of the invention before it has beenencapsulated. The microelectronic device 10 can include a substrate 20and a microelectronic die 40 attached to the substrate 20 by an adhesive60. The microelectronic device 10 shown in FIG. 1 illustrates thesubstrate 20 and the die 40 before forming protective casings thatencapsulate the die 40 and portions of the substrate 20. The followingdescription is directed toward encapsulating a microelectronic die on aflexible substrate, but it is expected that several embodiments ofmethods and apparatuses in accordance with the present invention may beused to encapsulate a large variety of electrical and/or non-electricalarticles. Therefore, the following description with respect toencapsulating the microelectronic die 20 shown in FIGS. 1A-6 is for thepurpose of illustration only and it is not intended to limit the scopeof the invention.

The embodiment of the substrate 20 shown in FIG. 1A can have a first end21, a second end 22 opposite the first end 21, a first surface 23, and asecond surface 24 opposite the first surface 23. The substrate 20 canalso include an elongated slot 25 between the first and second surfaces23 and 24 that extends lengthwise along a medial portion of thesubstrate 20. Additionally, an aperture 26 through the substrate 20 canbe located at a secondary gate location that is generally proximate tothe second end 22 of the substrate 20. The substrate 20 is one componentof an interconnecting unit that provides a plurality of interconnects,such as an array of ball-pads, for coupling very small bond-pads on themicroelectronic die 40 to voltage sources, signal sources, and/or otherinput and output sources. The interconnects can be electrical componentsor optical components that transmit a signal. In the embodiment shown inFIG. 1A, the substrate 20 includes a plurality of interconnects definedby an array of ball-pads 27, an array of contact elements 28 proximateto the slot 25, and a trace 29 or other type of conductive line betweeneach ball-pad 27 and a corresponding contact element 28. The substrate20 can be a flexible material or a substantially rigid material, and thetraces 29 can be conductive lines that are printed on the substrate in amanner similar to printed circuit boards.

The embodiment of the microelectronic die 40 shown in FIG. 1A includes afirst side 41 attached to the second surface 24 of the substrate 20 bythe adhesive 60. The microelectronic die 40 can also include a pluralityof small bond-pads 42 and an integrated circuit 44 (shown schematically)coupled to the bond-pads 42. The bond-pads 42 are arranged in an arrayalong the first side 41 of the microelectronic die 40 so that thebond-pads 42 are aligned with or otherwise accessible through the slot25 in the substrate 20. A plurality of wire-bond lines 50 or other typesof connectors couple the bond-pads 42 on the die 40 to correspondingcontact elements 28 on the substrate 20. As such, the substrate 20distributes the very small bond-pads 42 to the larger array of ball-pads27. Referring to FIG. 1B, the die 40 can project away from the secondsurface 24 of the substrate 20.

Referring again to FIG. 1A, the contact elements 28, the bond-pads 42,and the connectors 50 are arranged in a cap-zone defined by an area thatis to be encapsulated by a protective casing. In the embodiment shown inFIG. 1A, the microelectronic device 10 has a first cap-zone over thefirst surface 23 of the substrate 20 shown by an area A×B. The cap-zonecan have a different configuration for a different type ofmicroelectronic device. In other embodiments, for example, the cap-zonecan be around the die 40 over the second surface 24 of the substrate.

The microelectronic device 10 shown in FIG. 1A can also include abarrier 30 disposed on the substrate 20. The barrier 30 is anothercomponent of the inter-connecting unit along with the substrate 20. Inthis embodiment, the barrier 30 has an opening 32 surrounding thecap-zone A×B on the substrate 20. The opening 32 in the barrier 30 canbe adjacent to the border of the cap-zone A×B to completely surround thecap-zone A×B. The barrier 30 can accordingly cover the ball-pads 27 onthe substrate, but the contact elements 28, the bond-pads 42, and thewire-bond lines 50 are exposed through the opening 32 of the barrier 30.In other applications, only a portion of the barrier 30 is adjacent toonly a portion of the cap-zone. The barrier 30, for example, could beadjacent to the elongated sides of the cap-zone along the contactelements 28 and the end of the cap-zone at the aperture 26, but thebarrier 30 may not cover the area at the first end 21 of the firstsurface 23 of the substrate 20. The barrier 30 is accordingly disposedon the substrate 20 outside of the cap-zone A×B so that at least aportion of the barrier 30 is adjacent to at least a portion of thecap-zone A×B. As explained in more detail below, the barrier 30 acts asa gasket that inhibits or prevents a thermosetting material from leakingoutside of the cap-zone between the substrate 20 and a mold assembly.

The barrier 30 is applied to or otherwise formed on the substrate 20before molding a protective casing over the cap-zone. In the embodimentshown in FIG. 1A, the barrier 30 is a thin film, such as a tape, that isadhered to the substrate 20, or a pliable polymeric coating that isdeposited onto the substrate 20. The barrier 30 can alternatively bemade from other materials. In one embodiment, the barrier 30 is a rollof tape having a plurality of apertures that is applied to a continuousstrip of substrate material having a plurality of slots so that eachopening of the tape surrounds a corresponding slot. The strip can be cutto form a separate interconnecting unit having one or more individualpairs of the substrate 20 and the barrier 30. In another embodiment, thebarrier 30 is an individual piece of tape applied to an individualsubstrate 20. In still another embodiment, the barrier 30 is a coatingof a polymeric material, rubber, or other compressible and/or pliablematerial that is deposited onto the substrate 20. Such coatings can bedeposited by screen printing techniques, or by spraying a layer ofmaterial on the substrate.

FIGS. 2A and 2B illustrate an embodiment of a method for encapsulatingthe microelectronic device 10 using a mold assembly having a first moldsection 200 and a second mold section 300. The first mold section 200has a bearing surface 220 and a wire-side cavity 224, and the secondmold section 300 has a bearing surface 320 and a die-side cavity 324.The wire-side cavity 224 is configured to form a first protective casingover the cap-zone A×B shown in FIG. 1A, and the die-side cavity 324 isconfigured to form a second protective casing over the die 40 shown inFIG. 1B. The second mold section 300 can also include a gate 326 and aninjection chamber 328 through which a flow “F” of mold compound (e.g.,thermosetting material) is injected into the die-side cavity 324.

During the molding process, the microelectronic device 10 is positionedin the mold assembly to align the die 40 with the die-side cavity 324and to align the cap-zone A×B with the wire-side cavity 224 (best shownin FIG. 2B). In this embodiment, the bearing surface 220 of the firstmold section 200 presses against a perimeter portion 34 of the barrier30, and the bearing surface 320 of the second mold section 300 pressesagainst the second surface 24 of the substrate 20. The bearing surface220 of the first mold section 200 can press against the perimeterportion 34 of the barrier 30 by injecting a mold compound into thedie-side cavity 324, as explained in U.S. patent application Ser. No.09/255,554, which is herein incorporated by reference. The flow of moldcompound F initially passes through the gate 326 of the second moldsection 300. The flow of mold compound F continues into the die-sidecavity 324 to create a first flow A₁ heading in a first direction towardthe second end 22 of the substrate 20. The first flow of mold compoundA₁ passes through the aperture 26 in the substrate 20 to generate asecond flow of mold compound B₁ that flows through the wire-side cavity224 of the first mold section 200. The second flow of mold compound B₁fills the slot 25 of the substrate 20 and flows in a second directionuntil it reaches a terminal end 227 of the wire-side cavity 224.

The barrier 30 on the substrate 20 is expected to inhibit or prevent themold compound from leaking between the first side 23 of the substrate 20and the bearing surface 220 of the first mold section 200. For example,as the pressure of the mold compound builds in the die-side cavity 324,the pressurized mold compound drives the substrate 20 toward the firstmold section 200 to press the perimeter portion 34 of the barrier 30against the bearing surface 220. The perimeter portion 34 of the barrier30 accordingly fills small voids or surface asperities on both the firstsurface 23 of the substrate 20 and the bearing surface 220 of the firstmold section 200. As such, the perimeter portion 34 of the barrier 30inhibits the mold compound from leaking at the second end 22 of thesubstrate 20. Moreover, as shown by FIG. 2B, the barrier 30 alsoinhibits or prevents the mold compound from leaking between thesubstrate 20 and the bearing surface 220 of the first mold section 200in a lateral direction L relative to the second flow of mold compound B₁(FIG. 2A). The barrier 30 accordingly prevents the mold compound frominadvertently covering the ball-pads 27 on the first surface 23 of thesubstrate 20 or fouling the mold assembly at the second end 22 of thesubstrate 20.

One expected advantage of the embodiment of the barrier 30 shown inFIGS. 1A-2B is that it is expected to reduce or prevent the moldcompound from leaking between the substrate 20 and the first moldsection 200. The bearing surface 220 of the first mold section 200 isthus less likely to be fouled by the mold compound, and the ball-pads 27are also less likely to be covered by mold compound. As a result, theembodiment of the microelectronic device 10 with the barrier 30 shownabove in FIGS. 1A-2B is expected to reduce the downtime for cleaning themold assembly and the number of rejected parts.

FIG. 3 illustrates the microelectronic device 10 after a firstprotective casing 72 has been formed over the cap-zone A×B. The barrier30 can remain on the substrate 20 in subsequent processing steps, suchas reflow processing, marking, and other post-encapsulation processes.The barrier 30 can accordingly protect the ball-pads 27 until solderballs are deposited onto corresponding ball-pad 27. As such, anotherexpected advantage of the microelectronic device 10 is that the barrier30 can protect the substrate 20 from being damaged in other processesafter fabricating the casings 72 and 74.

FIG. 4 is a top isometric view of a microelectronic device 410 inaccordance with another embodiment of the invention. In this embodiment,the microelectronic device 410 includes the substrate 20 and the die 40.The substrate 20 and the die 40 can be similar to the componentsdescribed above with reference to FIGS. 1A-2B, and thus like referencenumbers refer to like components in FIGS. 1A-4. The microelectronicdevice 410 can also include a barrier 430 having an opening 432 and aplurality of apertures 436. The opening 432 exposes the cap-zone A×Bsuch that at least a portion of the barrier 430 is adjacent to at leasta portion of the cap-zone A×B. The apertures 436 are arranged in apattern corresponding to the pattern of ball-pads 27 on the substrate20. Each aperture 436 exposes a corresponding ball-pad 27 such that asolder ball or a solder paste pad can be deposited onto the ball-pads 27without removing the barrier 30. The solder balls can be deposited ontothe ball-pads 27 using pen dispensers, and the solder paste pads can bedeposited into the apertures 436 of the barrier 430 using screenprinting techniques known in the art. In a typical application, aprotective casing is formed in the opening 432 of the barrier 430 tocover the slot 25 and the contact elements 28 in a manner similar to themethod set forth above with respect to FIGS. 2A and 2B. After aprotective casing is formed over the cap-zone A×B of the substrate 20,the microelectronic device 410 is removed from the mold assembly and thesolder balls or solder paste pads can be deposited onto the ball-pads27.

The embodiment of the microelectronic device 410 shown in FIG. 4 isexpected to prevent the mold compound from leaking between the substrate20 and the mold assembly in a manner similar to the microelectronicdevice 10 described above. The microelectronic device 410 is alsoexpected to enhance the protection of the substrate 20 in subsequentprocessing steps because the barrier 430 can remain on the substrate 120throughout a reflow procedure for melting the solder balls or the solderpaste pads. After the reflow procedure, the barrier 430 can be peeled oretched from the substrate 20 to remove the barrier 430 before attachingthe microelectronic device 410 to a printed circuit board or otherassembly. The barrier 430 also enhances the registration of the solderballs or solder paste pads with the ball-pads 27 by providing guidesthat prevent the solder from bridging between adjacent ball-pads 27.Therefore, the microelectronic device 410 is expected to enhance thethroughput and yield of packaged microelectronic devices.

FIG. 5A is a top isometric view and FIG. 5B is a bottom isometric viewof a microelectronic device 510 in accordance with still anotherembodiment of the invention. In this embodiment, the microelectronicdevice 510 has a first barrier 530 a disposed on the first surface 23 ofthe substrate 20 and a second barrier 530 b disposed on the secondsurface 24 of the substrate 20. The first barrier 530 a can besubstantially similar to the barrier 30 described above with referenceto FIG. 3. The first barrier 530 a can accordingly have an opening 532 aaround the first protective casing 72 such that the first barrier 530 ais outside of a first cap-zone on the first side 23 of the substrate 20.The second barrier 530 b can be similar to the first barrier 530 a, butthe second barrier 530 b has a second opening 532 b around a secondprotective casing 74 that encapsulates the die 40 (FIG. 1B) on thesecond surface 24 of the substrate 20. The second barrier 530 b isaccordingly outside of a second cap-zone defined by the secondprotective casing 74. As such, at least a portion of the first barrier530 a is adjacent to at least a portion of the first cap-zone defined bythe first protective casing 72, and at least a portion of the secondbarrier 530 b is adjacent to at least a portion of the second cap-zonedefined by the second protective casing 74.

The first and second barriers 530 a and 530 b shown in FIGS. 5A and 5Bcan define the outline of the perimeter or the entire volume of thefirst and/or second protective casings 72/74. Referring to FIG. 5A, theopening 532 a is configured to define the perimeter of the protectivecasing 72. The barriers can also define the entire volume of the casingsby having a thickness equal to the desired thickness of the protectivecasings. The thickness of a barrier can be set by laminating barriers ontop of each other or manufacturing the barriers with the full thicknessof the casings. One expected advantage of using the barriers to definethe perimeter and thickness of the protective casings is that thecasings can be formed using a flat tool (i.e. a mold without a cavity).Such flat tooling is generally not complex and it is much easier toclean compared to molds with cavities.

FIG. 6 is a top isometric view of a microelectronic device 610 inaccordance with another embodiment of the invention. The microelectronicdevice 610 includes the substrate 20 and the microelectronic die 40attached to the substrate 20. The microelectronic device 610 can alsoinclude a barrier 630 defined by a rim around the cap-zone A×B. Thebarrier 630 can be a piece of tape, a pliable seal, or a raised portionof the substrate 20. For example, the barrier 630 can be a ridge moldedor embossed onto the substrate 20, or the barrier 630 can be decal or apiece of tape that is attached to the first surface 23 of the substrate20. The barrier 630 can operate in a manner similar to the barrier 130described above with reference to FIG. 1A. The microelectronic device610 is accordingly expected to inhibit or otherwise prevent a moldingcompound from leaking between the substrate 20 and a mold assemblyduring a molding process for forming a protective casing in thecap-zone.

From the foregoing it will be appreciated that specific embodiments ofthe invention have been disclosed for purposes of enablement andillustration, but that various modifications may be made withoutdeviating from the spirit and the scope of the invention. Accordingly,the invention is not limited except by the appended claims.

1. A method of partially encapsulating a microelectronic device,comprising: coupling a die to a substrate, wherein the substratecomprises an encapsulation area; disposing a seal on a first side of thesubstrate, wherein at least a portion of the seal is positioned adjacentto the encapsulation area; engaging the seal with one or more mold unitsafter disposing the seal on the first side of the substrate; introducinga molding compound into the one or more mold units; and removing theseal from the substrate after introducing the molding compound into theone or more mold units.
 2. The method of claim 1 wherein: the sealcomprises a tape, and engaging the seal with one or more mold unitscomprises contacting a first surface of a first mold unit with the sealand contacting a second surface of a second mold unit with a second sideof the substrate; and introducing the molding compound into the one ormore mold units comprises injecting the molding compound into at leastthe second mold unit.
 3. The method of claim 1 wherein: the substratefurther comprises a second side attached to the die, a slot in thesubstrate defining a slot area that is smaller than the encapsulationarea and positioned inside the encapsulation area, a contact positionedon the first side of the substrate and located inside the encapsulationarea adjacent to an edge of the slot, the contact being in electricalcommunication with a pad positioned on the first side of the substrateoutside of the encapsulation area; and the encapsulation area furthercomprises a perimeter on the first side of the substrate between thecontact and the pad.
 4. The method of claim 3 wherein disposing the sealon the substrate further comprises covering the pad with the seal andthe molding compound is introduced while the seal covers the pad.
 5. Themethod of claim 1, further comprising: positioning the first side of thesubstrate in a first cavity of a first mold unit; positioning the die ina second cavity of a second mold unit; and injecting the moldingcompound into the second cavity through a portion of the substrate andinto the first cavity, wherein the molding compound forms a protectivecasing over the encapsulation area and the die.
 6. The method of claim 1wherein disposing the seal on the first side of the substrate comprisesapplying a removable seal to the first side of the substrate.
 7. Themethod of claim 1, wherein the seal has an opening and the methodfurther comprises inhibiting the molding material from leaking outbeyond a perimeter of the opening with the seal.
 8. A method ofdisposing a flowable material on a microelectronic device, the methodcomprising: positioning a die proximate to a substrate, wherein the dieand substrate are in electrical communication with each other, andwherein the substrate comprises a contact and a pad spaced apart fromthe contact; attaching a barrier to the surface of the substrate,wherein the barrier comprises an opening defining a cap-zone, whereinthe barrier at least partially covers the pad, and wherein the contactis positioned inside the cap-zone; disposing the flowable material on atleast a portion of the cap-zone; and removing the barrier from thesubstrate after disposing the flowable material on at least a portion ofthe cap-zone.
 9. The method of claim 8 wherein positioning the dieproximate to the substrate comprises attaching the die proximate to anopening in the substrate, the opening being at least as small as thecap-zone.
 10. The method of claim 8 wherein attaching the barrier to thesurface of the substrate comprises forming a raised surface of thesubstrate.
 11. The method of claim 8, further comprising: positioningthe substrate and the die in a mold unit; contacting a first moldsurface with the barrier on a first side of the substrate and contactinga second mold surface with a second side of the substrate; and injectingthe flowable material into the mold unit.
 12. The method of claim 8wherein attaching the barrier to the surface of the substrate comprisesdisposing a releasable barrier on the surface of the substrate.
 13. Themethod of claim 8, further comprising inhibiting the flowable materialfrom leaking out of the cap-zone with the barrier.
 14. A method forconstructing a microelectronic device, the method comprising:electrically coupling a die to a substrate, wherein the substratecomprises a plurality of contacts and a pad on a first side of thesubstrate, wherein the contacts define a cap-zone, wherein the pad isspaced apart from the cap-zone, and wherein the die is positioned on asecond side of the substrate proximate to a slot in the substrate;disposing a first gasket on the first side of the substrate, wherein thegasket is positioned at least partially adjacent to the cap-zone;positioning the die and substrate in a mold assembly after disposing thefirst gasket on the first side of the substrate; injecting a moldingcompound into the mold assembly; and removing the first gasket from thefirst side of the substrate after injecting the molding compound intothe mold assembly.
 15. The method of claim 14 wherein: positioning thedie and substrate in the mold assembly comprises placing the substratein a first cavity of the mold assembly and placing the die in a secondcavity of the mold assembly; and injecting the molding compound into themold assembly comprises (a) flowing the molding compound into the secondcavity through the slot in the substrate, and (b) forming a firstprotective casing over the contacts of the substrate and a secondprotective casing over the die on the second side of the substrate. 16.The method of claim 14, further comprising inhibiting the moldingcompound from leaking out of the cap-zone with the first gasket.
 17. Themethod of claim 16 wherein inhibiting the molding compound from leakingcomprises engaging the first gasket with a bearing surface of the moldassembly.
 18. The method of claim 14, further comprising disposing asecond gasket on the second surface of the substrate, wherein the secondgasket at least partially surrounds the die.
 19. The method of claim 18,further comprising engaging the first gasket with a first bearingsurface of the mold assembly and engaging the second gasket with asecond bearing surface of the mold assembly.
 20. The method of claim 14wherein disposing the first gasket on the first side of the substratecomprises attaching a gasket having an aperture generally aligned withthe pad of the substrate.
 21. The method of claim 14 wherein disposingthe first gasket on the first side of the substrate comprises applying aremovable gasket to the first side of the substrate.
 22. The method ofclaim 14 wherein disposing the first gasket on the first side of thesubstrate comprises applying at least one of a pliable thin tape, thinfilm, or polymeric coating to the first side of the substrate.